ITMI980479A1 - BRIDGED METALLOCENIC COMPLEX FOR THE (CO) POLYMERIZATION OF OLEFINS - Google Patents

Abstract

A "bridged" bis-cyclopentadienyl complex which can be advantageously used for the formation of a catalytic system active in the (co)polymerization of ethylene and other alpha -olefins is represented by means of the following formula (II): <CHEM> wherein: M represents a metal selected from titanium, zirconium or hafnium; A' and A'' each independently represent an anion containing an eta <5>-cyclopentadienyl ring coordinated to M; R' or R'' each independently represents a group of an anionic nature sigma -bound to the metal M; B represents an unsaturated bivalent organic residue having from 1 to 30 carbon atoms, bound, respectively, to the ring of group A' and to the -CH2- methylene group by means of unsaturated carbon atoms. This complex, combined with a suitable cocatalyst, forms a catalyst with a high activity in the polymerization of olefins, producing polymers with a high molecular weight, especially in the case of the copolymerization of ethylene with a second alpha -olefin. <IMAGE>

Description

BRIDGED METALLOCENIC COMPLEX FOR THE (CO) POLYMERIZATION OF OLEFINS

DESCRIPTION

The present invention relates to a bridged metal complex usable for the (co) polymerization of olefins.

More particularly, the present invention relates to a particular bridged metallocene complex of a transition metal, as well as a catalyst comprising said complex, or derived therefrom, suitable for polymerizing, or copolymerizing with each other, ethylene and the other α-olefins, possibly in combination with a suitable co-catalyst. The present invention also relates to a method for the preparation of said metallocene complex and the corresponding binders, as well as a polymerization process of the olefins using the same.

It is generally known in the art that ethylene, or α-olefins in general, can be polymerized or copolymerized by means of low, medium or high pressure processes with catalysts based on a transition metal, generally known as Ziegler type catalysts. -Natta. A particular class of catalysts active in the polymerization of olefins consists of the combination of an organic aluminum oxide derivative (in particular, polymeric methyl-aluminoxane or MAO) with a cyclopentadienyl derivative (metallocene) of a transition metal of groups 3 to 6 of the periodic table of the elements (in the form approved by the IUPAC and published by the “CRC Press Ine.” In 1989). Results of particular interest were obtained with the catalysts based on metallocenes of group 4, that is, definable, in the most general form, with the following formula (I):

where M represents a metal of group 4; each RA independently represents a group having anionic character such as, for example, a hydride, a halide, a phosphonate or sulfonate anion, an alkyl or alkoxy group, an aryl or aryloxy group, an amide group, a silyl group, etc .; "W" is an index that can assume the integer values 1 or 2 depending on whether the valence of M is 3 or 4; Cp represents a ligand of the η <5> -cyclopentadienyl type and is generally selected from the η <5> -cyclopentadienyl, η <5> -indenyl, η <5> -fluorenyl groups or a substituted derivative thereof; RB can assume, regardless of the nature of the other substituents, one of the meanings of both the ligand Cp and the groups RA. Also of particular interest in the known art are so-called "bridged" metallocenes (commonly called "bridged" with terminology derived from English) in which two Cp groups, the same or different from each other, are coordinated with the metal M and covalently bonded to each other through a divalent organic group. For a known preparation technique of the above compounds, please refer to the description by H. Sinn, W. Kaminsky, in Adv. Organomet. Chem., You. 18 (1980), p. 99 and U.S. Pat. 4,542,199.

These catalysts generally show a high catalytic activity, and a certain versatility when applied to the preparation of polyolefins with specific characteristics, especially as regards the stereochemical control of the polymerization of α-olefins such as propylene.

The introduction of a "bridge" group, in particular, allows to keep the two pentaapto-coordinated rings (η <5>) of the cyclopentadienyl ligand in a more rigid reciprocal position than in the case in which the bridge is absent. This modification allows to obtain polymers with peculiar characteristics, sometimes impossible to obtain with non-bridged metallocenes, depending on the catalytic composition and the olefia subjected to polymerization.

It is known that certain "bridged" metallocene catalysts are able to polymerize α-olefins with high stereospecificity. While the (Ind) 2ZrCl2 complex provides a polypropylene with a low isotacticity index [L.Resconi et al. Macromolecules 25, 6814-6817, (1992)], the corresponding catalysts with ethylidene and dimethylsilyl bridges (in the racemic isomeric form) give polypropylene with isotacticity of 99% and 97% respectively, as reported for example in German patents DE 3,743,321 and DE 3.443.087.

In EP-A publication 310.734, at least two of the aforesaid complexes of formula (I) are used in mixture with each other in order to obtain a polymer with a broad distribution of molecular weights (MWD> 3) and therefore more easily workable in an extruder. In “Makromoleculare Chemie”, vol. 194 (1993), pp. 1745-1755, "bridging" complexes are described supported on inorganic substrates (A1203, MgCl2) and used in the presence of trialkylaluminium AIR3, instead of MAO, in the polymerization of propylene, while in the patent application EP-A 418.044 complexes "a bridge "cationic, which are active in polymerization even in the absence of MAO.

The patent and scientific literature on bridged catalysts is very vast. The numerous structures studied and claimed are preferably based on Zr and Hf and contain, as pentaapto-coordinated ligands, cyclopentadienyl (Cp), indenyl (Ind) or fluorenyl (Flu) rings, possibly substituted with suitable groups in certain positions of the molecular skeleton , in order to improve the performance of the catalyst and the resulting polymer. Thus W. Spaleck et al., In “Angewandte Chemie, Int. Ed. Eng.”, Vol. 31 (1992), pp. 1347-1349, report that the catalyst

allows to obtain a polypropylene with a higher molecular weight if

on the indenyl ring a methyl substituent is placed in position 2, while, according to “Organometallics”, vol. 13 (1994), pp. 954-963, a further substitution with a naphthoic group in position 4, also increases the polymer yield and the tacticity index.

Numerous other examples are reported in the patent literature, for example in European applications EP-A 582.194, EP-A 537.130, ΕΡΆ 574.370 and EP-A 581.754.

Despite the numerous advantages with respect to the previous known art, represented by the so-called "classic" Ziegler-Natta catalysts, having an intrinsically heterogeneous and multicentric nature, even the catalysts based on metallocenes have some drawbacks, such as, for example, the production of polymers with a still insufficient average molecular weight, especially with polymerization processes at high temperatures. Moreover, also in the case of metallocenes, it is desirable to further improve the stereoselectivity in the polymerization of α-olefins with high temperature and pressure processes, of the order of 150-250 ° C and 50-100 MPa. Equally desirable would be a further increase in the activation and polymerization rate given by the catalytic system in those processes characterized by reduced residence times in the reactor.

Another not completely satisfactory aspect of the aforementioned catalysts also concerns their behavior in the copolymerization of ethylene to produce low density polyethylene or olefinic elastomers, always in connection with the difficulty of obtaining copolymers with sufficiently high molecular weights, suitable for their many industrial applications. . It is in fact known the need to operate with significant quantities of comonomer in order to insert the desired quantity in the copolymer, with a consequent increase in the speed of the chain transfer reaction, which is competitive with the polymerization, and obtaining unsatisfactory molecular weights. All the more reason this drawback becomes critical when one operates with high temperature polymerization processes in which the chain transfer reaction is already relevant in the absence of the comonomer. No less significant, in this context, is the quantity of co-monomer inserted, as well as the "way" of insertion, with reference to the formation of comonomer block sequences, rather than a more desirable statistical distribution of the same.

While various types of variously substituted η <5> -cyclopentadienyl ligands have been thoroughly investigated in the known art, in order to overcome the aforementioned drawbacks and improve their characteristics according to the specific applications, relatively few are the publications on the influence, in a polymerization process of the groups constituting the "bridge" between said ligands, which are substantially limited, in practice, to the - groups (with alkyl or aryl groups).

In the publication “Makromolekulare Chemie, Rapid Comm.”, Vol. 14 (1993), pp. 633-636, particular polymerization catalysts based on bis-η <5> -cyclopentadienyl complexes) containing a bridge between the two ligands consisting of a 1,3-phenylenedimethylene group are described. These complexes, although capable of polymerizing ethylene in the presence of MAO, nevertheless show poor solubility in aromatic and / or aliphatic hydrocarbons, and an activity significantly lower than that of the more common metallocene complexes, such as, for example,

Again in the publication “Acta Chimica Sinica”, you. 48 (1990), pp. 298-301, the preparation of some bis-cyclopentadienyl complexes of zirconium and titanium is reported, which contain a phenylenedimethylene bridge between the two cyclopentadienyl ligands. However, no mention is given in this publication on the possible use of such complexes in the polymerization of olefins.

In the European patent application EP-A 752.428, in the name of the Applicant, bridged metallocene complexes are described in which the two η <5> -cyclopentadienyl groups are bridged with a divalent group having formula

wherein A is a divalent unsaturated hydrocarbon group. Although these complexes allow to obtain discrete reaction rates in the formation of homo- and olefinic copolymers, their ability to insert the comonomer in the co-polymerization of ethylene is still unsatisfactory.

A new class of metallocene complexes containing particular "bridging" groups has now been found by the Applicant, which, in the presence of a suitable co-catalyst, are able to catalyze the (co) polymerization of α-olefins without incurring drawbacks mentioned above and giving a polymer with high yield and molecular weight.

Therefore a first object of the present invention is a metallocene complex having the following formula (II):

in which: M represents a metal selected from titanium, zirconium or hafnium;

each A 'or A "independently represents an organic group containing an η <5> -cyclopentadienyl ring having anionic character, coordinated to the metal M;

each R 'or R "independently represents an anionic group σ- bonded to the metal M, preferably selected from hydride, halide, a C1-C20 alkyl or alkylaryl group, a C3-C20 alkylsilyl group, a C5-C20 group cycloalkyl, a C6-C20 aryl or arylalkyl group, a C1-C20 alkoxyl or thioalkoxyl group, a C2-C20 carboxylate or carbamate group, a C2-C20 dialkylamide group and a C4-C20 alkylsilylamide group;

B represents an unsaturated divalent organic residue having from 1 to 30 carbon atoms, linked, respectively, to the cyclopentadienyl ring of group A 'and to the methylene group -CH2- by unsaturated atoms other than hydrogen.

A second object of the present invention is a process for the (co) polymerization of olefins, comprising the polymerization or copolymerization of ethylene and / or one or more α-olefins, under suitable conditions of pressure and temperature, in the presence of a catalyst obtained from combination (contact and reaction) of the above metallocene complex with a suitable activator (or cocatalyst) selected from those known in the art, particularly an organic compound of a metal M 'selected from boron, aluminum, gallium and tin, or a combination of said compounds.

Any further objects of the present invention will appear evident from the following description and examples.

The term "unsaturated atom", as used in the present description and in the claims, refers to atoms of an organic or metallorganic compound, which form a double bond, of the olefmic or aromatic type, with at least one other atom.

In the complexes of formula (II) of the catalysts of the present invention, the -B-CH2- group "bridges" the two cyclopentadienyl groups A 'and A "giving the molecule structure a pacular geometry, deriving from the intrinsic asymmetry of the" bridge ", And from the fact that said group B is linked to the rest of the structure of formula (II) by means of bonds adjacent to an unsaturated bond. It generally consists of an unsaturated organic group, cyclic or acyclic, containing from 1 to 30 carbon atoms , which can also comprise one or more non-metallic heteroatoms included in groups 14 to 17 of the periodic table of elements, preferably selected from Si, N, 0, S, P, Cl, Br and F, more preferably from Si, N, O and F. In a particular form, group B is an unsaturated C2-C20 hydrocarbyl group not containing heteroatoms.

Said unsaturated group B can be an olefmically unsaturated group characterized by a double bond such as, for example, a vinylidene group -C = C-, or a group -C = N- containing a heteroatom. Said olefinically unsaturated group can be linked respectively to the groups of the complex of formula (II) with the two atoms at the ends of the double bond, with "Z" configuration, as, for example, in the following "bridging" groups:

or it can comprise a single carbon atom bonded to both of the aforementioned groups, as for example in the case of groups B having the following formulas:

Group B according to the present invention can also consist of a phenylene group, preferably ortho-phenylene, possibly substituted on any of the remaining positions of the ring. Typical substituent groups are those compatible with the use of the complex of formula (II) in the polymerization catalysis of olefins, that is, those groups that do not react with the cocatalysts as hereinafter defined. Examples of such substituent groups are halogen, such as fluorine, chlorine or bromine, an alkyl group such as, for example, methyl, ethyl, bufyl, isopropyl isoamyl, octyl, benzyl, a C3-C12 alkylsilyl group such as, for example, trimethylsilyl, triethylsilyl or tributylsilyl, a cycloalkyl group such as cyclopentyl or cyclohexyl, an aryl group such as phenyl or toluyl, an alkoxy group such as, for example, methoxy, ethoxy, iso- or secbutoxy, or also groups forming a further cycle, saturated or unsaturated, condensed with the main ring. Specific, non-limiting examples of phenylene B groups are o-phenylene, 2,5-dimethyl-o-phenylene, 3,4-dimethyl-o-phenylene, 3-ethyl-phenylene, 3-octyl-o-phenylene, 3 , 4-difluoro-o-phenylene, 2-methoxy-o-phenylene, m-phenylene, 4,6-dimethyl-m-phenylene, 5-phenyl-m-phenylene, 1,2-naphthylene, 2,3-naphthylene , 1,3-naphthylene, 2,3-phenanthylene, etc ..

A further class of divalent groups B included in the scope of the present invention consists of the condensed aromatic groups in which the atoms bonded to the two groups -A'- and -CH2-A "- of the formula (II) are in the" peri "position on two adjacent aromatic rings. Groups belonging to this class are, for example, 1,8-naphthalene, 4,5-dimethyl-1, 8-naphthalene, 5,6-acenaphthylene, etc ..

According to the present invention, the groups R 'and R "of formula (II) each independently represent a group having an anionic character σ-bonded to the metal M Typical examples of R' and R" are hydride, halide, preferably chloride or bromide , a linear or branched alkyl group such as methyl, ethyl, butyl, isopropyl, isoamyl, octyl, decyl, benzyl, an alkylsilyl group such as, for example, trimethylsilyl, triethylsilyl or tributylsilyl, a cycloalkyl group such as cyclopentyl, cyclohexyl, 4-methylcyclohexyl, an aryl group such as phenyl or toluyl, an alkoxy or thioalkoxyl group such as methoxy, ethoxy, iso- or sec-butoxy, ethylsulfide, a carboxylate group such as acetate, trifluoroacetate, propionate, butyrate, pivalate, stearate, benzoate, or a group dialkylamide such as diethylamide, dibutylamide, or alkylsilyl-amide, such as bis (trimethylsilyl) amide or ethyltrimethylsilylamide. The two groups R 'and R "can also be chemically bonded together and form a cycle having from 4 to 7 atoms other than hydrogen, also including the metal M. Typical examples of this aspect are the divalent anionic groups such as the trimethylene group or tetramethylene, or the ethylenedioxy group. Groups R 'and R "particularly preferred for their accessibility and the ease of preparation of the complexes comprising them, are chloride, methyl and ethyl.

According to the present invention, each anionic group A 'or A "in formula (II) contains an η-cyclopentadienyl ring coordinated with the metal M, which is formally derived from a molecule of cyclopentadiene, substituted or non-substituted, by extraction of one ion H +. The molecular structure and the typical electronic and coordinative configuration of metallocene complexes of titanium, zirconium or hafnium generally comprising two η <5> -cyclopentadienyl groups has been widely described in the literature and is known to those skilled in the art.

In the most general form of the present invention, the "bridge" -B-CH2- in formula (II) can be bonded to any one of the carbon atoms of the cyclopentadienyl ring of groups A 'and A "respectively (provided that a valence is available bond), preferably in position 1 0 3, in case A 'and / or A "are constituted by condensed bicyclic groups, such as, for example, indenyl or tetrahydroindenyl.

Typically, each group A 'or A "of the above preferred complexes is represented by the following formula (III):

wherein each substituent independently represents hydrogen, halogen, preferably F, Cl 0 Br, an aliphatic or aromatic C1-C20 hydrocarbyl group, optionally comprising one or more heteroatoms other than carbon and hydrogen, especially F, Cl, O, S and Si, or, in which at least any two of the substituents, adjacent to each other, are joined together to form a saturated or unsaturated C4-C20 cyclic structure, comprising a bond of the cyclopentadienyl ring, said structure possibly containing one or more of the previously specified heteroatoms .

The known cyclopentadienyl, indenyl or fluorenyl groups and their homologues, in which one or more carbon atoms of the molecular skeleton (included or not in the cyclopentadienyl ring) are included in the above formula (IIJ) of the preferred A 'or A "groups, are substituted with halogen, preferably chlorine or bromine, a linear or branched alkyl group such as methyl, ethyl, butyl, isopropyl, isoamyl, octyl, decyl, benzyl, an alkylsilyl group such as, for example, trimethylsilyl, triethylsilyl or tributylsilyl, a cycloalkyl group such as cyclopentyl, cyclohexyl, 4-methylcyclohexyl, an aryl group such as phenyl or toluyl, an alkoxy or thioalkoxyl group such as methoxyl, ethoxy, iso- or sec-butoxy, ethylsulfide, or a dialkylamide group such as diethylamide, dibutylamide, or alkylsylamide such as bis (trimethylsilyl) amide or ethyltrimethylsilylamide. Said groups A 'or A "can also comprise more condensed aromatic rings, as in the case, for example, of 4, 5-benzoindenyl. Particularly preferred A 'or A "groups are the cyclopentadienyl, indenyl, 4, 5,6, 7-tetrahydroindenyl, fluorenyl groups and the corresponding methyl substituted groups.

Typical examples of complexes of formula (II) suitable for the purposes of the present invention are the compounds listed below, which however are in no way limiting the overall scope of the present invention.

In the previous formulas the abbreviations 1,8-Naft = 1,8-naphthalidenmethylidene, Me = methyl,, Bz = benzyl, Ind = indenyl, Flu = fluorenyl, THInd = 4,5,6, 7-tetrahydroindenyl, Cp have been used * = tetramethylcyclopentadienyl.

The preparation of the aforementioned complexes of formula (II) can be carried out according to one of the known methods described in the literature for Γ obtaining the "bridged" bis-cyclopentadienyl complexes of the transition metals, obviously modifying the methodologies so as to adapt them to obtaining the complex desired.

The most commonly used method comprises reacting a salt of the metal M (preferably a chloride) with a salt of an alkali metal with the dianion of the bis-cyclopentadienyl ligand having the desired structure. In the most general case, this binder has the general formula (IV):

in which A ', A "and B all have the general meaning previously specified for the complexes represented by the formula (II), with the obvious difference that, in this case, each cyclopentadienyl group A' or A" is not η < 5> -coordinated with the metal M, nor has an aromatic character, but constitutes a neutral radical with the adjacent hydrogen atom as represented in formula (IV).

Preferably the aforesaid radicals -AΉ and HA "- have a structure that can be schematically represented with the following formula (IV-bis):

in which: each substituent has the same meaning and the same preference criteria as the corresponding Ri group (i = 1, 2, 3 04) in formula (III), the hydrogen atom represented at the center of the cycle is indifferently linked to one any of the carbon atoms of the cyclopentadienyl ring, e

the dashed circle schematically represents the two conjugated double bonds on the remaining four atoms of the cyclopentadienyl ring.

Typical non-limiting examples of compounds of formula (IV) according to the present invention are 1- (1-indenyl) -2- (1-indenyl) methylbenzene, 1 - [1 - (4, 5,6,7-tetrahydro ) indenyl] -2- (1 -indenyl) methylbenzene, 1 - [1 - (4,5,6,7-tetrahydro) indenyl] -2- [1 - (4,5,6,7-tetrahydro) indenyl] methylbenzene, 1- (4,7-dimethyl-1-indenyl) -2- (4,7-dimethyl-lindenyl) methyl-benzene, 1- (cyclopentadienyl) -2- (cyclopentadienyl) methylbenzene, 1- (1 -indenyl ) -8- (1 -indenyl) methylnaphthalene.

Normally, the preparation of the complexes of formula (II) comprises two stages, in the first of which the ligand of formula (IV) is reacted with a lithium alkyl, such as lithomethyl or lithium butyl, or a corresponding magnesium derivative, in an inert solvent preferably constituted from an aromatic hydrocarbon or an ether, particularly tetrahydrofuran or diethyl ether. The temperature during the reaction is preferably kept below the ambient temperature to avoid the occurrence of secondary reactions. At the end of the reaction, the corresponding lithium salt of the cyclopentadienyl dianion is obtained.

In the second stage, the salt of the cyclopentadienyl dianion is reacted with a salt, preferably a chloride, of the transition metal M, still in an inert organic solvent and at a temperature preferably lower than room temperature, normally between -50 and 0 ° C. At the end of the reaction the complex of formula (II) thus obtained is separated and purified according to the known methods of organometallic chemistry. As known to those skilled in the art, the aforementioned operations are sensitive to the presence of air and must be carried out in an inert atmosphere, preferably under nitrogen or argon.

Numerous general and particular methods substantially attributable to the method described above are described in the literature, such as, for example, in the publications of D.J. Cardin “Chemistry of Organo Zr and Hf compounds” J. Wiley and Sons Ed., New York (1986); R. Halterman "Chemical Review", vol. 92 (1992) pp. 965-994; R.O. Duthaler and A Hafner "Chemical Review", vol. 92 (1992) pp. 807-832.

An original synthetic process has also been found by the Applicant for the preparation of a particular class of bis-cyclopentadienyl ligands included in formula (IV), in which the "bridge" B consists of an ortho-phenylene group and group A ' it is different from fluorene or substituted fluorene. Said process, which constitutes a further object of the present invention, allows to obtain the aforesaid binders with satisfactory yields and high purity, and also makes easily accessible those binders whose groups A 'and A "have different (asymmetrical) structures.

In accordance with the above, another object of the present invention is a method for the preparation of a compound having the following formula (V):

in which: each radical -ΑΉ or HA "- independently represents a cyclopentadienyl group included in the previous formula (IV-bis), with the condition that ΑΉ is different from fluorenyl or substituted fluorenyl, and

B 'represents a divalent organic radical having from 6 to 30 carbon atoms and comprising a benzene aromatic ring, the two valences of which are in ortho position (adjacent to each other) on said aromatic ring, characterized in that it comprises the following stages in succession ,

a) protection of the alcoholic group of an o-bromobenzyl alcohol having the formula in which B 'is defined as above, by reaction, with an enol-alkyl ether having from 3 to 10 carbon atoms, with alkyl and R <7> = hydrogen or alkyl , e.g. 2-methoxypropene, in the presence of a catalytic amount of an aprotic Lewis acid, preferably P0C13, with the formation of the corresponding gem-diether

b) metallation of the gem-diether obtained according to step (a) with an alkyl compound of lithium or magnesium having from 1 to 10 carbon atoms, for example butyllithium or diet the magnesium, in non-polar solvents at a temperature from 0 to 30 ° C , obtaining the corresponding lithium or magnesium salt,

by substitution of the bromine atom;

c) condensation of the salt thus obtained with a precursor of the -AΉ group consisting of a cyclopentenone of corresponding structure, in which the carbonyl oxygen is found on the carbon in the position of the cycle which is to be bound to the said magnesium or lithium salt, for example 1-indanones or 2-indanones, in THF at a temperature below -30 ° C, preferably between -50 and -100 ° C; followed by hydrolysis of the reaction mixture and elimination of water to obtain the compound having the following formula (V-bis):

or, preferably, the corresponding bicyclic spiroderivative by addition of the -OH group to the double bond in the alpha position with respect to B ';

in which the different symbols all have the meaning seen above.,

d) reaction of the compound of formula (V-bis), or of the corresponding spiro derivative, obtained as in step (c), with excess aqueous hydrochloric or hydrobromic acid, preferably a concentrated solution of HBr (> 25% by weight), at a temperature between 50 ° C and 130 ° C, preferably at the reflux temperature of the mixture, to form an ortho-cyclopentadienylbenzyl halide having the same structure as the compound of formula (V-bis), with the only difference that the -OH group is substituted with the corresponding halide -Cl or -Br, preferably Br,

e) contact and reaction of the cyclopentadienyl-benzyl halide obtained as in step (d) with an organometallic compound of lithium or magnesium having the formula with A "having the same meaning as the previous formula (V) and chosen from Cl, Br or A", for example indenyl, fluorenyl or cyclopentadienyl lithium as such or variously substituted, in a suitable solvent, preferably a THF / hexane mixture, at a temperature from 10 to 40 ° C, to form the desired binder.

A further aspect of the present invention therefore relates to a catalyst for the (co) polymerization of ethylene and of the other α-olefms, i.e. for the homo-polymerization of ethylene and of the other α-olefins, the co-polymerization of ethylene with one or more other co-polymerizable monomers, such as, for example, a-olefins, conjugated or non-conjugated diolefins, styrene derivatives, etc., the copolymerization of α-olefins with each other or with other monomers copolymerizable with them. This catalyst comprises, or is obtained by contact and reaction of, at least the following two components:

(i) at least one metallocene complex of formula (II), e

(ii) a co-catalyst consisting of at least one organic compound of an element Μ 'other than carbon and selected from the elements of groups 2, 12, 13 or 14 of the periodic table as previously defined.

In particular, according to the present invention, said element M 'is selected from boron, aluminum, zinc, magnesium, gallium and tin, more particularly boron and aluminum.

In a preferred embodiment of the present invention, component (ii) is an organo-oxygen derivative of aluminum, gallium or tin. This can be defined as an organic compound of M ', in which the latter is bonded to at least one oxygen atom and to at least one organic group consisting of an alkyl group having from 1 to 6 carbon atoms, preferably methyl.

According to this aspect of the invention, component (ii) is more preferably an aluminoxane. As is known, aluminoxanes are compounds containing AI-O-AI bonds, with variable O / Al ratio, obtainable in the technique by reaction, under controlled conditions, of an alkyl aluminum, or alkyl aluminum halide, with water or other compounds containing predetermined quantities of available water, as, for example, in the case of the reaction of aluminum trimethyl with aluminum sulfate hexahydrate, copper sulfate pentahydrate or iron sulfate pentahydrate. The aluminoxanes which can preferably be used for the formation of the polymerization catalyst of the present invention are oligo- or polymeric compounds, cyclic and / or linear, characterized by the presence of repeating units having the following formula:

wherein is an alkyl group, preferably methyl.

Preferably each aluminoxane molecule contains from 4 to 70 repetitive units which may not be all the same, but contain groups

different.

Said aluminoxanes, and particularly methylaluminoxane, are compounds which can be obtained by means of the known methods of organometallic chemistry, for example by adding trimethyl aluminum to a suspension of hydrated aluminum sulphate in hexane.

When used for the formation of a polymerization catalyst according to the present invention, the aluminoxanes are placed in contact with a complex of formula (II) in such proportions that the atomic ratio between Al and the metal M is in the range from 10 to 10000 and preferably from 100 to 5000. The sequence with which complex (i) and aluminoxane (ii) are brought into contact with each other is not particularly critical.

In addition to the aforementioned aluminoxanes, the definition of component (ii) according to the present invention also includes galloxanes (in which, in the previous formulas, gallium is present instead of aluminum) and stannoxanes, whose use as polymerization cocatalysts of olefins in the presence of metallocene complexes is known, for example, from US 5,128,295 and US 5,258,475.

According to another preferred aspect of the present invention, said catalyst can be obtained by contacting component (i) consisting of at least one complex of formula (II), with component (ii) consisting of at least one compound or a mixture of organometallic compounds of M 'capable of reacting with the complex of formula (II) extracting from this an σ-bonded group R' or R "to form on the one hand at least one neutral compound, and on the other hand an ionic compound consisting of a metallocene cation containing the metal M and a non-coordinating organic anion containing the metal M ', whose negative charge is delocalized on a multicentric structure.

Components (ii) suitable as ionizing systems of the aforementioned type are preferably selected from the voluminous organic compounds of boron and aluminum, such as, for example, those represented by the following general formula:

in which the subscript "x" is an integer between 0 and 3, each group

independently represents an alkyl or aryl radical having from 1 to 10 carbon atoms and each group independently represents a partially or, better, totally fluorinated aryl radical, having from 6 to 20 carbon atoms.

Said compounds are generally used in quantities such that the ratio between the M atom in component (ii) and the M atom in the metallocene complex is in the range from 0.1 to 15, preferably from 0.5 to 10, more preferably 1 to 6.

Component (ii) may consist of a single compound, usually an ionic compound, or of a combination of such compound with MAO, or, preferably, with a trialkyl aluminum having from 1 to 8 carbon atoms in each alkyl residue, such as , for example,

In general, the formation of the ionic metallocene catalyst according to the present invention is preferably carried out in an inert liquid medium, more preferably hydrocarbon. The choice of components (i) and (ii) which are preferably combined with each other, as well as the particular methodology used, may vary according to the molecular structures and the desired result, as widely reported in the literature of the species accessible to the expert of the art.

Examples of these methodologies are qualitatively schematized in the list below, which does not, however, have any limiting character of the overall scope of the present invention;

(m1) by contact of a metallocene having the previous general formula (II) in which at least one, and preferably both, the substituents R 'and R "is hydrogen or an alkyl radical, with an ionic compound whose cation is capable of reacting with one of said substituents to form a neutral compound, and whose anion is bulky, non-coordinating and capable of delocalizing the negative charge;

(m2) by reaction of a metallocene having the above formula (II) with an alkylating agent, preferably a trialkyl aluminum, used in molar excess from 10/1 to 300/1, followed by the reaction with a strong Lewis acid, such as, eg. tris (pentafluorophenyl) boron in an almost stoichiometric quantity or in slight excess with respect to the metal M;

(m3) by contact and reaction of a metallocene having the previous formula (II) with a molar excess from 10/1 to 1000/1, preferably from 100/1 to 500/1 of an aluminum trialkyl or an alkylaluminium halide representable with the formula, in which R is a linear or branched alkyl group, or a mixture thereof, X is a halogen, preferably chlorine or bromine, and "m" is a decimal number between 1 and 3; followed by the addition to the composition thus obtained of at least one ionic compound of the type mentioned above in quantities such that the ratio between B or AI and the atom M in the metallocene complex is in the range from 0.1 to 15, preferably from 1 to 6.

Examples of ionizing ionic compounds or multicomponent reactive systems capable of producing an ionic catalytic system by reaction with a metallocene complex according to the present invention are described in the following patent publications, the content of which is incorporated herein by reference:

European patent applications, published under N .. EP-A 277.003, EP-A 277.004, EP-A 522.581, EP-A 495.375, EP-A 520.732, EP-A 478.913, EP-A 468.651, EP-A 427.697 , EP-A 421.659, EP-A 418.044;

international applications published under N .: WO 92/00333, WO 92/05208; WO 91/09882.

- patents US 5064802, US 2827446, US 5066739.

Non-limiting examples of complex-co-catalyst combinations suitable for the preparation of ionic catalytic systems in accordance with the present invention are schematized below in table (1), with reference to the respective precursors from whose combination they can be obtained. Any compound of each column can be combined, if necessary, with any compound of the remaining ones, according to the method indicated.

Table 1

Also included in the scope of the present invention are those catalysts comprising two or more complexes of formula (1) in admixture with each other. Catalysts of the present invention based on mixtures of complexes having different catalytic activities can be advantageously used in polymerization when a wider distribution of the molecular weights of the polyolefins thus produced is desired.

According to another aspect of the present invention, in order to produce solid components for the formation of the polymerization catalysts of the olefins, the aforesaid complexes can also be supported on inert solids, preferably consisting of Si and / or Al oxides, such as, for example , silica, alumina or silicoaluminates. For the support of said catalysts, known support techniques can be used, normally comprising the contact, in a suitable inert liquid medium, between the support, possibly activated by heating at temperatures above 200 ° C, and one or both components ( i) and (ii) of the catalyst of the present invention. It is not necessary, for the purposes of the present invention, for both components to be supported, since only the complex of formula (II), or the organic compound of B, Al, Ga or Sn as defined above, may be present on the surface of the support. In the latter case, the missing component on the surface is subsequently placed in contact with the supported component, at the moment in which the active catalyst for polymerization is to be formed.

Also included in the scope of the present invention are the complexes, and the catalytic systems based on them, which have been supported on a solid by functionalization of the latter and the formation of a covalent bond between the solid and a metallocene complex included in the previous formula (II).

A particular way of forming a supported catalyst according to the present invention comprises pre-polymerizing a relatively small fraction of monomer or monomer mixture in the presence of the catalyst, so as to include it in a solid microparticulate which is then fed to the actual reactor. and precisely for the completion of the process in the presence of further a-olefin. In this way a better control on the morphology and the dimensions of the polymeric particulate obtained at the end is obtained.

One or more other additives or components can optionally be added to the catalyst according to the present invention, in addition to the two components (i) or (ii), to obtain a catalytic system suitable for satisfying specific requirements in practice. The catalytic systems thus obtained are to be considered included in the scope of the present invention. Additives or components which may be included in the preparation and / or formulation of the catalyst of the present invention are inert solvents, such as, for example, aliphatic and / or aromatic hydrocarbons, aliphatic and aromatic ethers, weakly coordinating additives (Lewis bases) selected, for example, among non-polymerizable olefins, ethers, tertiary amines and alcohols, halogenating agents such as silicon halides, halogenated hydrocarbons, pref. chlorinated, and the like, and all other possible components normally used in the art for the preparation of traditional homogeneous metallocene catalysts for the (co) polymerization of ethylene and a-olefins.

Components (i) and (ii) form the catalyst according to the present invention by contact with each other, preferably at temperatures ranging from room value to 60 ° C and for times ranging from 10 seconds to 1 hour, more preferably from 30 seconds to 10 minutes .

The catalysts according to the present invention can be used with excellent results substantially in all known (co) polymerization processes of a-olefins, both continuously and batchwise, in one or more stages, such as, for example, low ( 0.1 - 1.0 MPa), medium (1.0 - 10 MPa) or high (10-150 MPa) pressure, at temperatures between 20 and 240 ° C, possibly in the presence of an inert diluent. As the molecular weight regulator, hydrogen can conveniently be used.

Said processes can be carried out in solution or suspension in a liquid diluent normally constituted by a saturated aliphatic or cycloaliphatic hydrocarbon having from 3 to 8 carbon atoms, but which can also be constituted by a monomer, as, for example, in the known process of co-polymerization of ethylene and propylene in liquid propylene. The quantity of catalyst introduced into the polymerization mixture is preferably selected so that the concentration of the metal M is comprised between <8> moles / liter.

Alternatively, the polymerization can be carried out in the gas phase, for example in a fluidized bed reactor, normally at pressures from 0.5 to 5 MPa and temperatures from 50 to 150 ° C.

According to a particular aspect of the present invention, the catalyst for the (co) polymerization of ethylene and α-olefins is prepared separately (preformed) by contacting components (i) and (ii), and subsequently introduced into the polymerization environment . The catalyst can be introduced into the polymerization reactor first, and then the reactant mixture containing the olefin or the mixture of olefins to be polymerized, or the catalyst can be introduced into the reactor already containing the reactant mixture, or, finally, the reactant mixture and the catalyst can be fed simultaneously to the reactor.

According to another aspect of the present invention, the catalyst is formed in situ, for example by introducing components (i) and (ii) separately from each other in the polymerization reactor containing the selected olefin monomers.

The catalysts according to the present invention can be used with excellent results in the polymerization of ethylene to give linear polyethylene and in the copolymerization of ethylene with propylene or higher α-olefins, preferably having from 4 to 10 carbon atoms, to give copolymers having different characteristics depending on the specific polymerization conditions and the quantity and structure of the α-olefin itself. For example, linear polyethylenes can be obtained with densities ranging from 0.880 to 0.940, and with molecular weights ranging from 10,000 to 2,000,000. The α-olefins used preferably as ethylene comonomers in the production of linear low or medium density polyethylene (known by the abbreviations ULDPE, VLDPE and LLDPE depending on the density), are 1-butene, 1-hexene and 1-octene.

The catalyst of the present invention can also be conveniently used in the copolymerization processes of ethylene and propylene to give saturated elastomeric copolymers vulcanizable by peroxides and very resistant to aging and degradation, or in the terpolymerization of ethylene, propylene and a non-conjugated diene having from 5 to 20 carbon atoms, to obtain vulcanizable rubbers of the EPDM type. In the case of the latter processes, it has been found that the catalysts of the present invention allow to obtain polymers having a particularly high diene content and average molecular weight under the polymerization conditions.

If EPDMs are to be prepared, the dienes useful for the preparation of these terpolymers are preferably selected from:

- linear chain dienes such as 1,4-hexadiene and 1,6-octadiene;

- branched dienes such as 5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene; 3,7-dimethyl- 1,7-octadiene;

- single ring dienes such as 1, 4-cioclohexadiene; 1,5-cyloottadiene; 1,5cyclododecadiene;

- dienes with bridged rings such as dicyclopentadiene; bicycle [2.2.1] hepta-2,5-diene; alkenyl, alkylidene, cycloalkenyl and cycloalkylidene norbomenes such as 5-methylene-2-norbomene, 5-ethylidene-2-norbomene (ENB), 5-propenyl-2-norbornene.

Among the unconjugated dienes typically used to prepare these copolymers, the dienes containing at least one double bond in a tensioned ring are preferred, even more preferably 5-ethylidene-2-norbornene (ENB), and also 1,4-hexadiene and the 1,6-octadiene.

In the case of the EPDM terpolymers, the amount of diene monomer conveniently does not exceed 15% by weight, and is preferably from 2 to 10% by weight. The propylene content, on the other hand, is conveniently comprised between 20 and 50% by weight.

The catalysts of the present invention can also be used in the processes of homo- and co-polymerization of α-olefins according to known techniques, to give atactic, isotactic or syndiotactic polymers with excellent yields, depending on the structure and geometry of the metallocene complex of formula ( II). α-Olefins suitable for this purpose are those having from 3 to 20 carbon atoms, possibly also including halogens or aromatic nuclei such as, for example, propylene, 1-butene, 1-hexene, 4-methyl-lpentene, 1 -decene and styrene .

The present invention is. further described by the following examples, which however are reported for purely illustrative and non-limiting purposes of the overall scope of the invention itself.

EXAMPLES

In the following examples, the analytical techniques and characterization methodologies listed below and briefly described were used.

The characterization by means of spectroscopy mentioned in the following examples, was carried out on a nuclear magnetic resonance spectrometer mod. Bruker MSL-300, using CDC13 as the solvent for each sample.

The measurement of the molecular weights of the olefinic polymers was carried out by Gel-Permeation Chromatography (GPC). The analyzes of the samples were performed in 1,2,4-trichloro-benzene (stabilized with Santonox) at 135 ° C with a WATERS 150-CV chromatograph using a Waters differential riffactometer as a detector.

The chromatographic separation was obtained with a set of μ-Styragel HT (Waters) columns, three of which with pore size

respectively, and two with pore size setting an eluent flow rate of 1 ml / min.

The data were acquired and processed using the Maxima 820 software version 3.30 (Millipore); the calculation of the number (Mn) and weight (Mw) average molecular weights was carried out by universal calibration, choosing polystyrene standards with molecular weights in the range 6.500.000 - 2.000 for the calibration.

The determination of the structures by X-rays of the new complexes in accordance with the present invention was performed on a Siemens AED diffractometer.

The mechanical properties of the products were determined by subjecting the copolymers to vulcanization. Of all these analyzes, the corresponding method adopted and, when available, the methodology reported in the technical literature is provided below.

The determination of the content of units deriving from propylene and any diene in the polymers is carried out (according to a methodology of the Applicant) by IR on the same polymers in the form of a film with a thickness of 0.2 mm, using a FTIR Perkin-Elmer spectrophotometer model 1760. The intensity of the characteristic peaks respectively of propylene at 4390 cm <-1> and of ENB at 1688 cm <-1>, relative to the peak at 4255 cm <-1>, is measured, and the quantity determined using a standard curve calibration.

The melt index (Melt Flow Index, MFI) of the polymers is determined in accordance with the ASTM D-1238 D.

The Mooney viscosity (1 + 4) is determined at 100 ° C using a Monsanto “1500 S” viscometer, according to the ASTM D 1646/68 method.

As regards the determination of the mechanical properties, these analyzes were performed on vulcanized copolymers. Below are (A) the vulcanization recipe and (B) the dynamo-mechanical determinations carried out according to the methods indicated therein.

A) Vulcanization

The vulcanization compounds were prepared using the formulation reported in the following Table 2.

TABLE 2

The mixture, homogenized on a roller mixer, is vulcanized between the plates of a press subjected to a pressure of 18 MPa and kept at 165 ° C for 40 minutes.

B) Mechanical characterization.

The mechanical characteristics of the vulcanized copolymers were determined on dumb-bell specimens obtained from the vulcanized plates.

The measurement of the breaking load was performed according to the ASTM D 412-68 method, the elongation at break according to the ASTM D 412-68 method, the Shore A hardness according to the ASTM D2240-68 method.

During the preparations reported in the examples, the following commercial reagents were used:

methyllithium (MeLi) 1.6 M in ALDRICH diethyl ether

butyllithium (BuLi) 2.5 M in hexane ALDRICH

FLUKA zirconium tetrachloride

indene FLUKA methylalumoxane (MAO) (Eurecene 5100 10T, WITCO

10% weight / volume of Al in toluene)

0-bromo-benzyl alcohol ALDRICH

2-methoxypropene ALDRICH

1-indanone ALDRICH

The reagents and / or solvents used and not listed above are those of common use and can easily be traced to the usual commercial operators specialized in the sector.

EXAMPLE 1: Synthesis of o-benzylidenebis- (η <5> -1-indenyl) zirconium dichloride 1) Synthesis of 1 - (1 -indenyl) -2-methylen- (1 -indenyl) -benzene (formula VI) To a mixture of 14 g of o-bromo-benzyl alcohol (75 mmol) and 72 ml of 2-methoxypropene (75 mmol) 0.4 ml of phosphorus oxychloride is added

acting as a catalyst. The alcohol slowly dissolves. You leave

stirring for two hours at room temperature. It is neutralized with triethylamine and dried to obtain about 20 g of an oily residue essentially consisting of 2-methoxy-2- (o-bromobenzyloxy) propane.

The residue is diluted with 150 ml of hexane and 30 ml of 2.5 M BuLi in hexane are added. A precipitate is formed. The mixture is left to stand for two hours, then it is filtered and washed with hexane, obtaining at the end the salt 2 - [(1-methyl-1-methoxy) ethioxymethyl] phenyl lithium.

10 g of 1-indanone (75 mmoles) dissolved in 50 ml of THF are added to the lithium salt dissolved in 100 ml of THF and cooled to -70 ° C. It is left to go to room temperature overnight. The mixture is then poured into water, 50 ml of aqueous HC1 1.1 are added and it is left under stirring for two hours. It is extracted with ether, the extract is washed with bicarbonate until neutral. By evaporation of the solvent and elution on a silica gel column using petroleum ether containing 10% ethyl acetate, 7.6 g of the spirobenzofuran derivative are obtained having the following structural formula (VI) :.

Following the following reaction scheme (I), 6.5 g of spirofuran derivative (V) (29 mmoles) are suspended in 50 ml of aqueous HBr at 48% by weight and the mixture thus formed is kept under stirring for 50 hours at room temperature. . It is then diluted with 10 ml of water and extracted with ethyl ether. The organic phase is separated, neutralized and dried by evaporation of the ether. The semisolid residue is purified by silica gel column chromatography, eluting with a 9: 1 mixture of petroleum ether-methylene chloride. At the end, after evaporation of the eluent, 6.1 g of o- (1-indenyl) -benzyl bromide (21 mmoles) are isolated.

Reaction scheme (Il

To a solution of 4 g of indene (34 mmoles) in a mixture consisting of 100 ml of THF and 30 ml of n-hexane, 8 ml of 2.5 M solution of butyllithium in hexane (20 mmoles) are added at room temperature . It is left under stirring for 4 hours and then cooled to -80 ° C. 5.7 g of o- (1 -indenyl) -benzyl bromide (20 mmoles) obtained as above are then added to the mixture, and the temperature is allowed to rise to ambient value in about 2 hours. The mixture thus obtained is hydrolyzed and extracted with ethyl ether. The organic phase, after neutralization, drying and evaporation of the ether, leaves a residue that is purified by chromatography on a silica gel column, eluting with petroleum ether. At the end, after evaporation of the eluent, 5.7 g of a white solid are obtained which, after spectroscopic characterization, was found to be the desired product of formula (VII) (17 mmoles).

2) Synthesis of the zirconium complex (formula VIII)

1.74 grams of the compound of formula (VII), obtained as above (5.44 mmoles), dissolved in 50 ml of anhydrous ethyl ether, are introduced into a 100 ml tailed test tube equipped with a magnetic stirrer. . To this straw yellow solution, 8 ml of 1.6 M butyllithium in hexane (12.8 mmoles) are added by dropping at room temperature and stirred for about 10 hours. At the end the reaction mixture appears as an amaranth colored solution. The volume of this solution is reduced to 10 ml, after which 30 ml of anhydrous n-hexane are added. A suspension is immediately formed which is filtered, collecting the solid and subsequently washing it with three portions of 10 ml each of n-hexane. The dilithium derivative of compound (VII) thus obtained is dried under vacuum (about 10 Pa) and transferred, under an argon atmosphere, to a 100 ml tailed test tube containing 50 ml of toluene, obtaining a suspension which is cooled to 0 ° C. Separately, 1.5 g of ZrCL4 (6.44 mmoles) are weighed and introduced, under argon, into the toluene suspension. After about 1 hour of stirring at 0 ° C, the temperature is allowed to rise to room level. The stirring is continued for another 30 minutes, after which it is filtered on a porous septum, collecting the mother liquors that contain the desired complex. The residue is washed again with toluene (3x10 ml) and the washing waters are added to the mother liquors. The clear toluene solution thus obtained is left to rest for about two days at room temperature, with the formation of orange crystals. These are separated by filtration, washed with a little toluene and characterized by NMR and X-rays. 0.82 g of the desired complex (formula VIII) are obtained, with a yield of 31% with respect to the initial binder quantity.

The X-ray structure and spectrum

of the complex of formula (VIII) are shown in Figures 1 and 2 respectively.

Example 2: Synthesis of o-benzylidenebis- (5.6-dimethyl-η <5> -l -indenylzirconium dichloride 1) Synthesis of 5,6-dimethyl-1-indanone (Xa) and 5,6-dimethyl-indene (Xla)

To a solution of 164 g (1.23 moles) A1C13 in 500 ml of nitromethane, maintained under argon, a mixture of 69 g (0.543 moles) of 3-chloropropionyl chloride and 58 g (0.547 moles) of o-xylene, cooling with a water bath (25 ° C). Once the addition is complete, it is kept under stirring for 5 hours. At the end, the reaction mass is poured into 500 g of ice containing 100 ml of concentrated HCl. It is extracted with ethyl ether. The ethereal extracts are washed with 2N HCl and then with a saturated aqueous solution of NaCl until neutral. It is anhydrified with sodium sulphate and then the solvent is evaporated to obtain 106.3 g of compound (IX) (98% yield).

To 420 ml of concentrated H2SO4, 106.3 g of compound (IX) are slowly added. Once the addition is complete, the mixture is brought to 90 ° C, this temperature is maintained for 3 hours, and the mixture is then poured onto ice. It is extracted with toluene. The organic extracts are washed with a saturated solution of NaHC03 and finally with a saturated solution of NaCl until neutral. The solution is then treated with filtered activated carbon and dried over sodium sulphate. The residue obtained after evaporation of the solvent is recrystallized from petroleum ether to give 25 g (156 mmoles) of a 1: 1 mixture of 5,6-dimethyl- and 6,7-dimethyl-1-indanone Xa and Xb (29% yield).

To the solution in THE of 25 g (156 mmoles) of the mixture of I-indanones Xa and Xb obtained as above, 3.8 g (101 mmoles) of sodium boron hydride are added in portions, keeping the mixture under an inert atmosphere at 10 ° C. Once the addition is complete, it is left to rise to room temperature and stirred for 1 hour. The reaction mixture is then poured into water and ice and extracted with ethyl ether. A mixture is obtained containing both the reduction products Xla and Xlb shown in the diagram below. The ethereal extract is washed with water until neutral and anhydrified on sodium sulfate. The residue obtained by evaporation of the solvent is recrystallized from petroleum ether to give 6.5 g of the isomer alone

6.5 g (0.401 moles) of 5,6-dimethyl-1-indanol (Xla), 10 g of silica (MERCK), 70 ml of toluene and 70 ml of heptane are introduced and mixed in a Markusson apparatus and heated to reflux, azeotropically removing the water formed. After 16 hours the reaction is complete. The mixture is filtered, diluted with ethyl ether, washed with water and the organic phase dried over sodium sulphate. After evaporation of the solvent, 5.2 g of 5,6-dimethyl-indene are obtained (90% yield).

2) Synthesis of 1- (5,6-dimethyl-1-indenyl) -2- (5,6-dimethyl-1-indenyl) methyl benzene (XIV)

Reaction scheme (I.

27 ml (0.067 moles) of n -BuLi 2.5 M in hexane. The mixture is left under stirring for 2 hours and then the hexane solution is decanted. The residual solid is washed again with hexane by decantation and then dissolved in THF.

It is cooled to -80 ° C and a solution of 11.0 g (0.068 moles) of 4,7-dimethyl-1-indanone (formula Xa) dissolved in 30 ml of THF is added. It is left to rise to room temperature overnight, then it is poured into water and ice to which 50 ml of 1: 1 HCl are added. It is kept under stirring at 0 ° C for 2 hours. It is extracted with ethyl ether which is subsequently washed until neutral, first with a saturated solution and then with water. After drying the organic phase on sodium sulphate, the solvent is evaporated. The residue is purified by silica gel column chromatography eluting with a mixture of hexane, ethyl acetate 9: 1. After evaporation of the eluent 7.0 g (0.028 moles) of the spirofuran derivative of formula (XII) are collected (see scheme II, 42% yield).

The above spirofuran derivative is placed in 48 ml of 48% HBr and the reaction mass is kept under reflux for 16 hours. At the end, after dilution with water, it is extracted with ethyl ether, and the ether phase is washed with a saturated sodium bicarbonate solution and then with water until neutral. After drying the organic phase on sodium sulphate and evaporation of the solvent, the residue obtained is purified by chromatography on a silica gel column, eluting with a mixture of hexane / ethyl acetate in a 9: 1 ratio. 5.3 g (0.0168 moles) of o- [1- (5,6-dimethyl) -indenyl] -benzyl bromide (formula XIII, scheme III, 60% yield) are thus obtained.

To 5.2 g (0.0388 moles) of 5,6-dimethyl-indene, obtained as above (formula Xia), dissolved in a mixture of 100 ml of THF and 50 ml of hexane, 14.4 ml (36.1 mmoles) of n- BuLi 2.5 M in hexane. After 2 hours from the end of the addition, it is cooled to -70 ° C and 5.3 g (0.0168 moles) of o- [1- (5,6-dimethyl) -indenyl] -benzyl bromide (formula XIII) dissolved in 50 ml of THF. At the end of the addition, it is brought to room temperature and left under stirring for 3 hours. It is poured into water slightly acidified with HC1 and then extracted with ethyl ether. The organic phase is neutralized by washing with water, anhydrified on sodium sulphate and then the solvent is evaporated. By purification of the residue on a silica gel column using petroleum ether as eluent 6.0 g of a solid are obtained which, after spectroscopic characterization, was found to be in the desired ligand: 1- (5,6-dimethyl- 1 -indenyl) - 2- (5, 6-dimethyl- 1 -indenyl) methyl benzene (formula XIV).

Reaction scheme (II

3) Synthesis of the zirconium complex

We proceed in a completely similar way to what is described in paragraph 2 of example 1, by reacting the same molar quantities of the bis-indenyl binder and zirconium tetrachloride, under the same process conditions. Therefore 1.95 grams of compound of formula (XIV) (5.2 mmoles) are reacted with 7.5 ml of lithium butyl solution, and subsequently with 1.45 g of ZrCl4, to obtain at the end 0.8 g of the desired complex having the underlying formula (XV).

Figure 3 shows the spectrum

of the complex of formula (XV).

1) Synthesis of 4,7-dimethyl-1-indanone (XVII) and 4,7-dimethyl-indene (XVHI)

Follow the procedure shown in diagram (IV). To a suspension of 16 g (0.120 moles) of AICI3 in 70 ml of methylene chloride, kept at 0 ° C in an inert atmosphere, a solution of 10 ml of 3-chlorpropionyl chloride in 14.5 g ( 0.136 mol) of p-xylene. At the end of the dripping, the temperature is allowed to rise to 10 ° C and it is maintained between 10-20 ° C for about 2 hours. The reaction mixture is poured on ice and extracted with methylene chloride. The organic extracts are washed with water until neutral and the organic phase, after separation, is anhydrified on sodium sulphate. After evaporation of the solvent, a residue essentially constituted by the compound of formula (XVI) reported in the following scheme (IV) is obtained.

The above residue is added to 90 ml of concentrated H2SO4 at a rate such as to maintain the temperature between 20 and 30 ° C. Once the addition is complete, the temperature is brought to 80 ° C and maintained for 2 hours under stirring. The mixture is then poured on ice and extracted with ethyl ether. The ethereal solution is washed to neutrality with a saturated sodium bicarbonate solution and then water and is finally dried over sodium sulphate. The solid obtained by evaporation of the ether is washed with petroleum ether and dried. Thus 20 g of 4,7-dimethyl-1-indanone are obtained (formula XVII in the following scheme IV, 91% yield in the two steps).

Reaction scheme (V)

2.9g (0.0181 mol) of 4,7-dimethyl-1-indanone (formula XVII) are slowly added to a suspension of 0.350 g (0.0692 mol) d in 30 ml of ethyl ether, kept at -30 ° C in an inert atmosphere. ) obtained as specified above. After 30 minutes the reaction comes to completion. Ice and 2N HCl are carefully added until acidification, then extracted with ethyl ether, separating and subsequently washing the organic phase until neutral. It is dried on sodium sulphate and evaporated, obtaining a residue essentially consisting of 4,7-dimethyl-1-indanol. The residue is dissolved in 10 ml of THF, a spatula tip of ptoluenesulfonic acid is added and refluxed for 1 hour. Solid NaHC03 and Na2SO4 are then added. The solvent is filtered and evaporated to obtain 2.4 g of 4,7-dimethyl-indene (XVII) (91% yield).

2) Synthesis of 1- (4,7-dimethyl-1-indenyl) -2- (4,7-dimethyl-1-indenyl) methyl benzene (XXI)

Reaction scheme (V)

To 20 g of 2-methoxy-2- (o-bromobenzyloxy) propane (77.22 mmoles) obtained as in Example 1.1, in a solution of 150 ml of hexane, 30 ml of n-BuLi 2.5 M in hexane (75 mmoles ). Once the addition is complete, it is left to stir for 2 hours. There is precipitation of the corresponding lithium salt, as previously reported in example 1. The hexane is decanted and the solid is further washed with hexane and then dissolved in 100 ml of THF. It is cooled to -70 ° C and then 12.12 g (75.75 mmoles) of 4,7-dimethyl-1-indanone obtained as above, dissolved in THF as required, are slowly added. It is then left to rise to room temperature overnight, the reaction mass is poured into ice, acidified with 50 ml of 1/1 aqueous HC1 and stirred for 2 hours. It is extracted with ethyl ether and the organic phase is washed until neutral with a solution of sodium bicarbonate and water. It is dried on sodium sulphate. After evaporation of the solvent, the residue is purified by chromatography on a silica gel column, eluting with a mixture of hexane / ethyl acetate 9: 1. After evaporation of the eluent, 10 g of the alcohol having formula (XIX) are obtained (scheme V; 53% yield).

Reaction scheme (VP

To a solution of 6.0 g of the alcohol of formula (XIX) (24 mmoles) in 50 ml of methylene chloride, kept at 0 ° C, PBr3 is added in small portions, checking the progress of the reaction by means of thin layer chromatography (TLC ), until the alcohol disappears. At the end, a saturated solution of Si is added drop by drop, at 0 ° C, then extracted with 100 ml of methylene chloride and the extracts are washed until neutral. The residue obtained after anhydrification and evaporation of the solvent is purified by chromatography on silica gel eluting with a mixture of hexane / ethyl acetate 9: 1. After evaporation of the eluent 4.0 g of the brominated compound of formula (XX) are obtained in the scheme (VI) (52% yield).

4.12 ml (10.3 mmoles) of n-BuLi 2.5 are added to a solution of 1.48 g of 4,7-dimethyl indene (XVIII) (10.3 mmoles; obtained as above) in 55 ml ml of a mixture of THF-hexane 2/1 M in hexane. Once the addition is complete, it is left to stir for 1 hour. It is then cooled to -70 ° C and then a solution of 2.3 g of the brominated compound of formula (XX) (7.37 mmoles) in THF / hexane is dropped. It is left to rise to room temperature and left to rest for 6 hours. The mixture is then poured into water and extracted with ethyl ether. The organic phase is washed until neutral and dehydrated over sodium sulphate. The residue obtained by evaporation of the solvent is purified by chromatography on silica gel eluting with petroleum ether. After evaporation of the eluent 2.0 g of the bis-indenyl binder of formula (XXI) are obtained (72% yield).

3) Synthesis of the zirconium complex (formula XXII)

We proceed in a completely similar way to what is described in paragraph 2 of example 1, by reacting the same molar quantities of the bis-indenyl binder and zirconium tetrachloride, under the same process conditions. Therefore 1.95 grams of compound of formula (XXI) (5.2 mmoles) are reacted with 7.5 ml of lithium butyl solution, and subsequently with 1.45 g of ZrCl4, to obtain at the end 0.9 g of the desired complex having the underlying formula (XXII).

Figure 4 shows the spectrum of the complex of formula (XXII).

Examples 4-9: Ethylene / propylene / ethylidennorbornen ter-polymerization Examples 4 to 9 refer to a series of ter-polymerization tests for the preparation of an EPDM type elastomeric copolymer based on ethylene / propylene / ethylidennorbornene, carried out using a preformed catalytic system comprising on the one hand the metallocene complex o-benzylidenebis- (η <5> -l-indenyl) -zirconium dichloride, obtained as previously described in Example 1, and on the other hand methylalumoxane (MAO) as co - catalyst. The specific polymerization conditions of each example and the results obtained are shown in Table 3 below, in which the number of the reference example, the quantity of zirconium used, the atomic ratio between aluminum in the MAO and zirconium, the pressure appear in succession. of polymerization, the initial molar concentration of ethylidennorbornene (ENB) in liquid propylene, the activity of the catalytic system with reference to zirconium, the relative quantity, by weight, of the monomer units C2, C3 and ENB in the polymer, the weight average molecular weight and the dispersion of molecular weights

The polymerization is carried out in a 0.5 liter pressure reactor, thermostated and equipped with a magnetic drive stirrer, the reactor is previously tempered in the usual way, by washing with a dilute solution of MAO in toluene (about 0.1 M in Al) and vacuum drying (0.1 Pascal for a few hours).

At room temperature, 120 g of polymerization grade liquid propylene and the quantity of ENB necessary to reach the desired concentration are loaded into the reactor. The reactor is then brought to the polymerization temperature of 40 ° C, and, by means of a float, gaseous ethylene is introduced until the desired equilibrium pressure (22-28 atm) of the liquid mixture is reached, maintained under moderate stirring. Under these conditions, the molar concentration of ethylene in the liquid phase is between 12 and 24%, depending on the total pressure of the system, as can be easily calculated using the appropriate liquid-vapor equilibrium tables.

In a suitable tailed test tube, maintained under nitrogen, 10 ml of toluene are introduced and components (i) and (ii) are added, in suitable quantities for the preparation of the desired catalytic composition. In particular, the desired quantity of the aforementioned metallocene complex is introduced as a toluene solution about 1x10 <-3> molar, and then the MAO is added as a 1.5 molar solution (as Al) in toluene (commercial product Eurecene 5100 10T by the company Witco ), in such a quantity that in the resulting catalytic mixture the molar ratio of aluminum / zirconium is between 3700 and 4000, as specified in Table 3. The solution of the catalyst thus formed is kept at room temperature for a few minutes and then transferred under a flow of gas inert in a metal container from which, due to nitrogen overpressure, it is transferred to the reactor.

The polymerization reaction is carried out at 40 ° C taking care to keep the pressure constant by continuously feeding ethylene to compensate for the part reacted in the meantime. After five minutes the ethylene feeding is interrupted, the monomers are degassed and the polymer is recovered after devolatilization of the monomers still present at 60 ° C under vacuum (about 1000 Pa). The solid thus obtained is weighed and the activity of the catalyst is calculated as kilograms of polymer per gram of metallic zirconium per hour.On the solid, dried and homogenized, the weight average molecular weight Mw and numeral and the content of the different monomer units C3 are measured. (propylene) and ENB, using the known techniques based on IR spectroscopy. The results are reported in table 3.

Examples 10-14: Ethylene / propylene copolymerization and terpolymerization with END

Some ethylene / propylene co-polymerization and ter-polymerization tests with ENB were carried out, using the same preformed catalytic system of the previous examples from 4 to 9. The specific polymerization conditions of each example and the results obtained are shown in Table 4 below. , in which the reference example number, the quantity of zirconium used, the atomic ratio between aluminum in the MAO and zirconium, the polymerization pressure, the initial molar concentration of ethylidennorbornene (ENB) in the liquid propylene appear in succession, the quantity of hydrogen initially introduced, the effectiveness of the catalytic system with reference to zirconium, the relative quantity, in moles, of the monomer units C2, C3 and ENB in the polymer, the MOONEY viscosity of the polymer measured at 100 ° C, and the mechanical characteristics of the polymer (only for EPDM) after vulcanization (load at break C.R .; elongation at break A.R., Shore hardness A at 160 ° C).

The polymerization is carried out in a 3 liter pressure reactor, thermostated and equipped with a magnetic drive stirrer. The reactor is reclaimed by washing with about 500g of liquid propylene, containing about 2g of aluminum triisobutyl (TIBA). The mixture is discharged, and the reactor again washed with a little fresh propylene and emptied.

About 800 g of "polymerization grade" liquid propylene and the amount of ENB necessary to reach the desired concentration are loaded into the reactor, and then about 1 ml of a 0.3 molar solution of TIBA in hexane is introduced with the sole function of scavenger . A small amount of hydrogen is optionally added as a molecular weight regulator. The reactor is brought to the polymerization temperature of 45 ° C, and, by means of a float, gaseous ethylene is introduced until the desired equilibrium pressure (22-28 atm) of the liquid mixture is reached, maintained under moderate stirring. Under these conditions the molar concentration of ethylene in the liquid phase is about 12-20%, depending on the total pressure of the system.

In a suitable tailed test tube, maintained under nitrogen, 10 ml of toluene are introduced and components (i) and (ii) are added, in suitable quantities for the preparation of the desired catalytic composition. In particular, the desired quantity of the metallocene complex obtained as in example 1 is introduced, as an approximately molar toluene solution, and then the MAO is added in such a quantity that in the resulting catalytic mixture the molar ratio of aluminum / zirconium is between 6000 and 7000. , as specified in Table 4. The solution of the catalyst thus formed is kept at room temperature for a few minutes and then transferred under a flow of inert gas into a metal container from which, under nitrogen overpressure, it is transferred to the reactor.

The polymerization reaction is carried out at 45 ° C, taking care to keep the pressure constant by continuously feeding ethylene to compensate for the part reacted in the meantime. After 1 hour the ethylene feed is interrupted, the residual monomers are degassed and the autoclave is rapidly cooled to room temperature. The polymer is recovered and the devolatilization of the monomers is completed by calendering at about 80 ° C. The solid copolymer thus obtained is weighed and the activity of the catalyst is calculated as kilograms of polymer per gram of metal zirconium per hour

Said copolymers are characterized by the content of monomer units, determined by IR spectroscopy and by some mechanical properties measured after vulcanization carried out according to the previously described method. The results of the characterization and the polymerization conditions are shown in the following Table 4.

The examples show that the catalytic systems obtained starting from the metallocene complexes of the present invention are active for the production of elastomeric ethylene-propylene copolymers and ethylene-propylene-diene terpolymers with high Mooney viscosity.

Example 15: (comparative)

A polymerization test was carried out in the same apparatus and with the same modalities of the previous example 10, but using the 1,2-ethylene bis (η <5> -1-indenyl) zirconium dichloride complex (commercial product WITCO), as component of the catalytic system in place of the o-benzylidene bis (η <5> -1-indenyl) -zirconium dichloride complex of the present invention, and under the process conditions specified in the following table 4. The co-polymers thus obtained were characterized as described in precedence and the results obtained are summarized in the following Table 4.

NOTES: (1) Comparative example; (2) Temperature = 40 ° C, (3) measured at 125 ° C;

(4) feed 250 g propylene and 550 g propane; n.m. = not measured

TABLE 4: Copolymerization and terpolymerization of ethylene

Examples 16-19: ethylene / propylene copolymerization and terpolymerization with ENB

A series of ethylene / propylene / ENB co- and ter-polymerization tests are conducted in a 60 liter reactor equipped with a water circulation thermostatic jacket, mechanical stirrer and a continuous monomer feeding system, connected by means of a foot valve to a 600 liter stripper for devolatilization of the obtained polymer. For a more effective temperature control, the reactor is also equipped with a special section that allows the continuous extraction of a part of the vapor phase which is condensed and reintroduced into the reactor as a liquid.

The composition of the reaction mixture, kept in liquid / vapor equilibrium, is determined with a frequency of 6 minutes by means of an automatic vapor phase analysis system with a COMBUSTION ENGINEERING model 3100 gas chromatograph, equipped with a Chromosorb 10260/80 column. .

In the reactor, thermostated at 45 ° C, the monomers and propane are introduced up to a volume of liquid of 35 liters, adjusting the respective quantities so that the composition of the vapor phase is that shown in the following table 5. In these conditions the pressure total is normally between 1.5 and 2.0 MPa.

The catalyst is prepared separately, as a solution in toluene, by mixing the desired quantities of MAO (in toluene at 10% by weight) and of the o-benzylidene bis- (η <5> -1-indenyl) zirconium dichloride complex (0.1 % weight / volume in toluene), in order to respect the proportions shown in table 5.

About 4.3 g (28 mmoles) of aluminum triisobutyl in hexane solution (13% weight / volume) are introduced into the reactor with the function of scavenger. The stirring is maintained for a few minutes and the catalyst solution is then introduced using a suitable container connected to the reactor and pressurized with anhydrous nitrogen.

At this point the polymerization is carried out for the duration of one hour, keeping the temperature constant at 45 ° C and continuously feeding a further quantity of monomers in order to keep the composition of the vapor in equilibrium with the liquid. At the end, the content of the reactor is discharged into the stripper containing about 300 liters of water at room temperature and the residual monomers and propane are removed by evaporation. The remaining aqueous suspension is filtered, and the polymer obtained is dried in a calender and characterized. The results are reported in table 5.

('): measured at 125 ° C

TABLE 5: copolymerization and terpolymerization of ethylene

Example 20: ethylene / 1-hexene copolymerization

I) Preparation of the catalyst

A solution of the polymerization catalyst according to the present invention is prepared separately, by dissolving 23 mg (0.048 mmoles) of the complex of formula (VIII) in 50 ml of anhydrous toluene prepared according to the previous example 1, and adding to this mixture, at room temperature , 3 ml of a solution of MAO at 10% by weight in toluene (title in Al = 1.57M) so that the atomic ratio Al / Zr is approximately equal to 100. The solution is matured by leaving it under stirring for 30 minutes at room temperature, before being introduced into the polymerization mixture.

Il) Polymerization

900 ml of toluene (previously distilled on metallic sodium ), 60 ml of 1-hexene (previously distilled on calcium hydride, CaH2) and 1.5 ml of the aforementioned 10% MAO solution in toluene. It is pressurized with ethylene at 0.2 MPa and heated to 40 ° C.

The autoclave is depressurized and 1.1 ml of the catalyst solution prepared as above are introduced in an ethylene stream, so as to have an atomic ratio of 2500 between the zirconium as a whole and the total aluminum contained in the MAO ( resulting from the sum of that introduced with the catalyst solution and that introduced directly into the autoclave). The autoclave is brought again under pressure to 2 atm with ethylene and the polymerization is carried out for 30 minutes, thermostating at 40 ° C and continuously feeding ethylene in order to maintain constant pressure for the entire duration of the test. At the end, the reaction is interrupted by adding 5 ml of acidified methanol, the polymer is depressurized and the polymer is recovered by precipitation with 3 liters of acidified methanol and subsequent washing with acetone. After drying, 15 g of an ethylene / 1-hexene co-polymer (LLDPE) are obtained with the following characteristics:

number average molecular weight (Mn) 122,000 and weight (Mw) 327,000, molecular weight distribution (MWD = Mw / Mn): 2.7

monomer units derived from 1-hexene (1-hexene inserted): 8% reactivity product of the monomers (ri r2): 0.64

surrender:

Example 21: ethylene / 1-octene copolymerization

An ethylene / 1-octene co-polymerization test is carried out by operating exactly the same procedure and the same materials of the previous example 20, but using 75 ml of 1-octene instead of 60 ml of 1-hexene.

At the end, after drying, 11 g of an ethylene / 1-octene co-polymer (LLDPE) are obtained having the following characteristics:

number average molecular weight (Mn) 164,000 and weight (Mw) 362,000, molecular weight distribution (MWD = Mw / Mn): 2.2

monomer units derived from 1-octene (1-octene inserted): 7.3% by weight product of reactivity of the monomers

surrender:

Example 22: high temperature polymerization

A polymerization test is carried out in a 1 liter steel adiabatic reactor, capable of operating up to about 100 MPa and at temperatures between 160 and 220 ° C.

Two streams are fed to the reactor, respectively containing the monomers and the catalyst solution, keeping the flow rates at a value such as to allow a residence time of about 40 seconds. The conversion per pass, and consequently the temperature, is controlled and regulated by the flow rate of the catalyst solution, so as to maintain a polymer production in the range of 3-4 kg / h.

The catalyst solution is prepared by dissolving 550 mg (1.14 mmol) of the o-benzylidene bis- (η <5> -l-indenyl) zirconium dichloride complex, prepared according to Example 1 above, in 90 ml of toluene, and adding 150 ml of a solution of MAO in toluene (title in Al = 4.5 M) (ratio Al / Zr = 600). Said solution is kept under stirring at room temperature for about 1 hour, and then diluted by adding 1800 ml of Isopar-L before being introduced into the reactor. The concentration of Zr in the solution fed is 0.507 mM. The stream containing the monomers consists of ethylene for 64% by volume and 1-butene for 46%. The polymerization temperature is maintained at a constant value around 160 ° C and the pressure is set at 80 MPa.

Under these conditions, an ethylene-butene copolymer (LLDPE) is obtained having the following characteristics:

Number of short branches (Short Chain Branching) = 8.3 / (1000 C); Melting point = 120.1 ° C.

The catalytic activity was 9,200

Example 23: Catalyst in ionic form

In a BUCHI-type autoclave, with a steel reactor with a capacity of 2 liters, equipped with an anchor stirrer and a thermostatic jacket with liquid circulation, previously reclaimed and dried in vacuum (0.1 Pa) for at least two hours, they are introduced into the order: 1 liter of heptane and 250 g of propylene. The mixture is heated to 50 ° C and, under stirring, ethylene is introduced by means of a float, until a total pressure of 1.3 MPa is reached,

Separately, 1.0 ml of a 1.2 M solution of aluminum triisobutyl in toluene, and 4 ml of an M solution of o-benzylidenebis- (η <5> - l-indenyl) zirconium dichloride obtained according to the previous example 1. After having kept the solution under stirring for 15 minutes at room temperature, 3 ml of a solution M in toluene of tetrakis- (pentafluorophenyl) triphenylcarbenium borate are added and immediately transferred the solution obtained in a special container placed above the autoclave, from which, by pressurization with nitrogen, it is pushed into the reactor. Polymerization begins almost immediately and is continued for 30 minutes, maintaining the temperature at 50 ° C and the pressure at 1.3 MPa by continuous ethylene feeding. At the end, after degassing the residual monomers, the polymer is recovered by coagulation by adding 1 liter of methanol, filtration and subsequent drying. 90.5 g of an ethylene / propylene co-polymer are thus obtained having a content of propylene units of 26.9% by weight, average molecular weight Mn = 100,000 and dispersion - 1.8. The activity of the catalyst is

was

Claims (23)

CLAIMS 1. Metallocene complex, usable in the formation of a catalyst for the (co) polymerization of ethylene and α-olefins, having the following formula (II): in which: M represents a metal selected from titanium, zirconium or hafnium; each A 'or A "independently represents an organic group containing an η <5> -cyclopentadienyl ring having anionic character, coordinated to the metal M; each R 'or R "independently represents a group having an anionic character σ-bonded to the metal M; B represents an unsaturated divalent organic residue having from 1 to 30 carbon atoms, linked, respectively, to the ring of group A 'and to the methylene group -CH2- by unsaturated atoms other than hydrogen. 2. Complex according to claim 1, wherein at least one of the groups A 'and A ", preferably both, is selected from tetrahydro) indenyl. Complex according to one of claims 1 or 2, wherein said metal M is zirconium. 4. Complex according to any one of the preceding claims, wherein said divalent organic residue "B" is selected from the ortho-phenylene groups having from 6 to 20 carbon atoms, or peri-naphthalene having from 10 to 20 carbon atoms. 5. Complex according to any one of the preceding claims, wherein each of the R 'or R "groups in formula (II) is independently selected from hydride, halide, a C1-C20 alkyl or alkylaryl group, a C3-C20 alkylsilyl group, a C5-C20 cycloalkyl group, a C6-C20 aryl or arylalkyl group, a C1-C20 alkoxyl or thioalkoxyl group, a C1-C20 carboxylate or carbamate group, a C2-C2o dialkylamide group and a C4-C20 alkylsilylamide group. 6. Catalyst for the (co) polymerization of ethylene and other a-olefins, comprising at least the following two components in contact with each other: (i) at least one metallocene complex according to any one of the preceding claims 1 to 5, e (ii) a co-catalyst consisting of at least one organic compound of an element M 'other than carbon and selected from the elements of groups 2, 12, 13 or 14 of the periodic table. 7. Catalyst according to claim 6, wherein said component (i) is constituted by a metallocene complex according to the previous claim 4. 8. Catalyst according to one of claims 6 or 7, wherein said element M 'in component (ii) is selected from boron, aluminum, zinc magnesium gallium and tin, more particularly boron and aluminum. 9. Catalyst according to any one of the preceding claims, wherein said component (ii) is a polymeric aluminoxane, preferably methylalfuminoxane. 10. Catalyst according to claim 9, wherein the atomic ratio between the metal M in the complex of formula (II) and Al in the aluminoxane is between 100 and 5000. 11. Catalyst according to any one of claims 6 to 8, wherein said component (ii) consists of at least one compound or a mixture of organometallic compounds of M 'capable of reacting with the complex of formula (II) by extracting from this a σ-bonded group R 'or R "to form on the one hand at least one neutral compound, and on the other hand an ionic compound consisting of a metallocene cation containing the metal M and a non-coordinating organic anion containing the metal M', whose negative charge is delocalized on a multicentric structure. 12. Catalyst according to claim 11, wherein the atomic ratio between the metal M 'in component (ii) and the metal M in component (i) is between 1 and 6 13. Catalyst according to claim 11 or 12, wherein said component (ii) is constituted by an ionic-ionizing compound selected from the group of compounds having one of the following formulas: in which: the subscript "x" is an integer between 0 and 3; each group independently represents an alkyl or aryl radical having from 1 to 10 carbon atoms and each RD group independently represents a partially or totally fluorinated aryl radical, having from 6 to 20 carbon atoms. 14. Catalyst according to claim 13, wherein said component (ii) comprises, in addition to said ionizing-ionizing compound, an alkyl aluminum of formula, wherein R is an alkyl group, linear or branched, X is chlorine or bromine, and "m" is a decimal number comprised between 1 and 3, preferably 3, with a ratio between B or Al in the ionizing compound and A1 in the aluminum alkyl comprised between 100 / and 500/1. 15. Process for the (co) polymerization of ethylene or α-olefins, both continuously and batchwise, in one or more stages, at low (0.1 - 1.0 MPa), medium (1.0 - 10 MPa) or high (10-150 MPa) pressure, at temperatures between 20 and 240 ° C, possibly in the presence of an inert diluent, characterized in that at least ethylene or at least one α-olefin is placed in contact, in a of the above conditions, with a catalyst according to one of the preceding claims from 6 to 14. 16. Process according to claim 15, wherein ethylene is copolymerized with at least one α-olefin having from 3 to 10 carbon atoms. 17. Process according to claim 16, wherein, in addition to said at least one α-olefin, a non-conjugated, aliphatic or alicyclic diene having from 5 to 20 carbon atoms is co-polymerized with ethylene. 18. Process according to any one of the preceding claims from 15 to 17, characterized in that it is carried out in solution or suspension in a suitable inert liquid medium consisting of an aliphatic or cycloaliphatic hydrocarbon having from 3 to 15 carbon atoms, or of a mixture of sayings. 19. Process according to any one of the preceding claims from 15 to 17, characterized in that it is carried out in the absence of inert diluent. 20. Process according to any one of the preceding claims from 15 to 19, characterized in that the concentration of the metal M of formula (II) in the polymerization mixture is comprised between moles / liter. 21. Bis-cyclopentadienyl compound usable as binder for the formation of the complexes of formula (II) in claim 1, having the following general formula (IV): in which B represents an unsaturated divalent organic residue having from 1 to 30 carbon atoms, linked, respectively, to the ring of group A 'and to the methylene group with -CH2- by unsaturated atoms other than hydrogen, and each group A'H or A "H independently represents a neutral organic radical containing a cyclopentadienyl ring that can be represented by the following formula (IV-bis): wherein each substituent independently represents hydrogen, halogen, an aliphatic or aromatic C1-C20 hydrocarbyl group, optionally comprising one or more eternatoms other than carbon and hydrogen, especially F, Cl, O, S and Si, or, in which at least any two of the substituents R1, R2, R3 and R4, adjacent to each other, are joined together to form a saturated or unsaturated C4-C20 cyclic structure, comprising a bond of the cyclopentadienyl ring, said structure possibly being able to contain one or more than the previously specified heteroatoms., e the hydrogen atom represented in the center of the cycle is linked indifferently to any of the carbon atoms of the cyclopentadienyl ring, and the dashed circle schematically represents the two conjugated double bonds on the remaining four atoms of the cyclopentadienyl ring. 22. Bis-cyclopentadienyl compound according to the preceding claim 21, characterized by the following formula (V): in which. each group A'H or A "H independently represents a neutral organic radical containing a cyclopentadienyl ring that can be represented by the following formula (IV-ter): wherein each substituent independently represents hydrogen, halogen, an aliphatic or aromatic C1-C20 hydrocarbyl group, optionally comprising one or more heteroatoms other than carbon and hydrogen, especially F, Cl, O, S and Si, or, in which at least any two of the substituents adjacent to each other are joined together to form a saturated or unsaturated C4-C20 cyclic structure, comprising a bond of the cyclopentadienyl ring, said structure possibly being able to contain one or more of the previously specified heteroatoms, with the provided that ΑΉ is different from fluoroenyl or substituted fluoroenyl, e the hydrogen atom represented at the center of the cycle is linked indifferently to any of the carbon atoms of the cyclopentadienyl ring, and the dashed circle schematically represents the two conjugated double bonds on the remaining four atoms of the cyclopentadienyl ring, and B 'represents a divalent organic radical having from 6 to 30 carbon atoms and comprising a benzene aromatic ring, the two valences of which are in an ortho position on said aromatic ring. 23. Process for the preparation of a bis-cyclopentadienyl compound of formula (V) according to the previous claim 22, characterized in that it comprises the following steps in succession: a) protection of the alcoholic group of an o-bromobenzyl alcohol having formula, in which B 'is defined as above for the formula (V), by reaction with an enol-alkyl ether having from 3 to 10 carbon atoms, with = hydrogen or alkyl, in the presence of a catalytic amount of an aprotic Lewis acid, preferably, with the formation of the corresponding gem-diether ^ O b) metallation of the gem-diether obtained according to step (a) with an alkyl compound of lithium or magnesium having from 1 to 10 carbon atoms, in an apolar solvent at a temperature from 0 to 30 ° C, obtaining the corresponding lithium salt or magnesium, by substitution of the bromine atom; c) condensation of the salt thus obtained with a precursor of the -AΉ group consisting of a cyclopentenone of corresponding structure, in which the carbonyl oxygen is found on the carbon in the position of the cycle that is to be bound to the said magnesium or lithium salt, in a polar aprotic solvent, preferably THF, at a temperature below -30 ° C, preferably between -50 and -100 ° C; followed by hydrolysis of the reaction mixture and elimination of water to obtain the compound having the following formula (V-bis): or, preferably, the corresponding bicyclic spiroderivative, by adding the -OH group to the double bond in the alpha position with respect to B '; in which the different symbols all have the meaning seen above .; d) reaction of the compound of formula (V-bis), or of the corresponding derivative spiro, obtained as in step (c), with excess aqueous hydrochloric or hydrobromic acid, at a temperature between 50 ° C and 130 ° C, to form a ortho-cyclopentadienyl-benzyl halide having the same structure as the compound of formula (V-bis), with the only difference that the -OH group is substituted with the corresponding halide -Cl or -Br, e) contact and reaction of the cyclopentadienyl-benzyl halide obtained as in step (d) with an organometallic compound of lithium or magnesium having formula HA "(Li or MgR <8>), with A" having the same meaning as the previous formula (V ) and R <8> selected from Cl, Br or A ", in a suitable solvent, preferably a THF / hexane mixture, at a temperature from 10 to 40 ° C, to form the desired egant